Composite flywheel

ABSTRACT

A flywheel includes a wheel having a composite rim structure with multiple radial layers of steel material. Epoxy type adhesive can bond the multiple layers of stainless steel together.

RELATED APPLICATION

This application is a Divisional of U.S. application Ser. No.13/230,399, filed on Sep. 12, 2011, and claims the benefit of U.S.Provisional Application No. 61/382,694, filed on Sep. 14, 2010. Theentire teachings of the above applications are incorporated herein byreference.

BACKGROUND

Composite flywheels can include fibers, or filaments that are wound intoa wheel and bonded together with adhesives. Such fibers can be metallicwires. The size, or speed of composite flywheels having metallic wiresis typically limited to being relatively small, so that the wires andadhesive do not delaminate from each other.

SUMMARY

The present invention can provide a flywheel that can be made larger andheavier, and rotated at higher speeds than prior composite flywheels.The flywheel can include a wheel having a composite rim structure withmultiple radial layers of stainless steel material. Epoxy type adhesivecan bond the multiple layers of stainless steel together.

In particular embodiments, the radial layers of stainless steel materialcan have a series of cavities. In some embodiments, the stainless steelmaterial can include a length of stainless steel fibers. The epoxy typeadhesive can be vacuum impregnated into spaces between the stainlesssteel fibers and the radial layers of the stainless steel material. Inone embodiment, the stainless steel material can include stainless steelwire rope. In another embodiment, the stainless steel material caninclude a web of stainless steel braided wire. In another embodiment,the stainless steel material can include a web of stainless steel mesh.The composite rim structure can be positioned around an outer perimeterof a core member. The core member can be mounted on a central shaft. Inone embodiment, the composite rim structure can have a series ofdiscrete concentric annular rings of stainless steel material. Inanother embodiment, the composite rim structure can have a continuousspiral wound length of stainless steel material. In other embodiments,multiple radial layers of nonmetallic fiber material can be included andpositioned such that adjacent radial layers of stainless steel materialhave a layer of the nonmetallic fiber material bonded therebetween. Thenonmetallic fiber material can be formed of carbon.

The present invention can also provide a flywheel including a wheelhaving a composite rim structure. The composite rim structure can havemultiple radial layers of porous steel web material and multiple radiallayers of porous nonmetallic fiber web material, forming alternatingradial layers of porous steel web material and porous nonmetallic fiberweb material. An adhesive can bond the alternating radial layers ofporous steel web material and porous nonmetallic fiber web materialtogether.

In particular embodiments, the porous steel web material and the porousnonmetallic fiber web material are wound from continuous lengths into abilayer spiral configuration. The porous steel web material can beformed from alloy steel, which in some embodiments is stainless steel.The porous nonmetallic fiber web material can be formed of carbon. Theporous steel web material can be in mesh form, and the porousnonmetallic fiber web material can be in cloth form. A metallic coremember can be included and have an outer perimeter around which thecomposite rim structure is positioned.

The present invention can also provide a flywheel including a wheelhaving a composite rim structure with multiple radial layers of surfacetreated steel material. An adhesive can bond the multiple radial layersof surface treated steel material together.

In particular embodiments, surfaces of the steel can be treated toremove rust and/or oil. In addition, surfaces of the steel can betreated to increase surface area bonding with the adhesive. In someembodiments, surfaces of the steel can be treated with a rust inhibitingprotective coating.

The present invention can also provide a method of forming a flywheelincluding forming multiple radial layers of stainless steel materialinto a wheel. The multiple radial layers of stainless steel material canbe bonded together with epoxy type adhesive to form a composite rimstructure of the wheel.

In particular embodiments, the radial layers of stainless steel materialcan be provided with a series of cavities. In some embodiments, thestainless steel material can be provided with a length of stainlesssteel fibers. The epoxy type adhesive can be vacuum impregnated intospaces between the stainless steel fibers and the radial layers of thestainless steel material. In one embodiment, the stainless steelmaterial can be stainless steel wire rope. In another embodiment, thestainless steel material can be a web of stainless steel braided wire.In another embodiment, the stainless steel material can be a web ofstainless steel mesh. The composite rim structure can be positionedaround an outer perimeter of a core member. The core member can bemounted on a central shaft. In one embodiment, the composite rimstructure can be formed with a series of discrete concentric annularrings of stainless steel material. In another embodiment, the compositerim structure can be formed with a continuous spiral wound length ofstainless steel material. In other embodiments, the composite rimstructure can include multiple radial layers of nonmetallic fibermaterial positioned so that adjacent radial layers of stainless steelmaterial have a layer of the nonmetallic fiber bonded therebetween. Theradial layers of nonmetallic fiber material can be formed from carbon.

The present invention can also provide a method of forming a flywheelincluding forming multiple radial layers of porous steel web materialand multiple radial layers of porous nonmetallic fiber web material intoa wheel, with alternating radial layers of porous steel web material andporous nonmetallic fiber web material. The multiple radial layers ofporous steel web material and multiple radial layers of porousnonmetallic fiber web material can be bonded together with an adhesiveto form a composite rim structure of the wheel.

In particular embodiments, the porous steel web material and the porousnonmetallic fiber web material can be wound from continuous lengths intoa bilayer spiral configuration. The porous steel web material can beformed from alloy steel, which in some embodiments, can be stainlesssteel. The porous nonmetallic fiber web material can be formed fromcarbon. The porous steel web material can be in mesh form and the porousnonmetallic fiber web material can be in cloth form. The composite rimstructure can be positioned around an outer perimeter of a metallic coremember.

The present invention can also provide a method of forming a flywheelincluding forming multiple radial layers of surface treated steelmaterial into a wheel. The multiple radial layers of surface treatedsteel material can be bonded together with an adhesive to form acomposite rim structure of the wheel.

In particular embodiments, surfaces of the steel can be treated toremove rust and/or oil. In addition, surfaces of the steel can betreated to increase surface area for bonding with the adhesive. In someembodiments, surfaces of the steel can be treated with a rust inhibitingprotective coating.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of example embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments of the present invention.

FIG. 1 is a perspective view of an embodiment of a flywheel system inthe present invention.

FIG. 2 is a front view of an embodiment of a flywheel in the presentinvention.

FIG. 3 is a perspective view of the flywheel of FIG. 2 with the coreomitted.

FIG. 4 is a perspective view of the flywheel of FIG. 2.

FIG. 5 is a sectional view of the flywheel of FIG. 2.

FIG. 6 is an enlarged view of a portion indicated by reference numeral 6in FIG. 5.

FIG. 7 is an exploded perspective view of a flywheel being loaded withinan embodiment of a vacuum chamber housing or enclosure in the presentinvention.

FIG. 8 is a front view of the flywheel loaded within the vacuumenclosure.

FIG. 9 is a side view of the flywheel loaded within the vacuum enclosureand connected to a vacuum pump and a reservoir of adhesive.

FIG. 10 is a perspective view of an embodiment of one half of a vacuumchamber housing or enclosure in the present invention, such as the upperhalf.

FIG. 11 is a front view of the vacuum chamber half of FIG. 10.

FIG. 12 is a side view of the vacuum chamber half of FIG. 10.

FIG. 13 is a sectional view of the vacuum chamber half of FIG. 10.

FIG. 14 is a bottom view into the interior of the vacuum chamber half ofFIG. 10.

FIG. 15 is a perspective view of an embodiment of a flywheel housing ona support frame.

FIG. 16 is a schematic perspective view of an embodiment of forming aflywheel in the present invention having wound wire rope.

FIG. 17 is a schematic perspective view of another embodiment of forminga flywheel in the present invention having concentric annular rings ofmesh.

FIG. 18 is a schematic perspective view of yet another embodiment offorming a flywheel in the present invention having wound mesh.

FIG. 19 is a schematic drawing of a process for forming anotherembodiment of a flywheel in the present invention.

FIG. 20 is a side schematic view of a portion of a flywheel formed bythe method of FIG. 19.

FIG. 21 is a schematic drawing depicting a portion of the layers of theflywheel of FIG. 19.

DETAILED DESCRIPTION

A description of example embodiments of the invention follows.

Referring to FIG. 1, an embodiment of a flywheel system or device 10includes a flywheel 12, which can be formed of composite materials. Theflywheel 12 can rotate about a lateral or horizontal support or driveshaft 18 having a longitudinal axis A, that is supported by bearings 17,and can be contained within a housing, chamber or enclosure 14. Theinterior of the housing 14 can have a vacuum to reduce wind resistanceon the flywheel 12. The housing 14 and bearings 17 can be supported ormounted on a support frame, base or platform 16. A drive unit 20 can berotatably connected to one end of the shaft 18 for driving the flywheel12 up to a desired speed. The drive unit 20 can have an electric motorwhich can be rotated up to a desired speed, and a variable speedtransmission. A generator unit 22 can be rotatably connected to theshaft 18 on the opposite end of shaft 18 for generating electricity fromthe rotation of the flywheel 12. The flywheel 12 can be brought up to adesired rotational speed to store energy, which can be converted toelectricity when desired, by generator unit 22. The generator unit 22can include a generator that is driven by a variable speed transmission.The variable speed transmission can allow the generator to be rotated ata desired constant rotational speed even while flywheel 12 changes orloses speed. Rotating the generator at a constant speed can provide aconstant electrical power output, which can be desirable. The generatorcan be a DC or AC generator, and when the generator is an AC generator,the generator can be rotated at a constant rotational speed, for example1800 RPM for producing electrical power having a frequency of 60 Hertz.In some embodiments, 1500 RPM can be suitable for 50 hertz. The flywheel12 can be rotated above about 1000 RPM, for example in some embodiments,in the range of about 3000 RPM to about 6000 RPM, and other embodiments,up to about 10,000 RPM.

Referring to FIGS. 2-6, the flywheel 12 can include an inner core orcore member 24 secured or mounted to or around the shaft 18, and anouter composite rim structure 26 secured, formed or mounted around thecore 24. The core 24 can be secured to the shaft 18 by two clampsecurement members, plates or flanges 28 that are on opposite sides orfaces 13 of the core 24 and flywheel 12. The plates 28 can be secured tothe core 24 and to shoulders on shaft 18 with threaded members such asthreaded rods, bolts, nuts, etc. In some embodiments, other suitablesecurement methods can be employed. In some embodiments, the core 24 canbe formed of polymeric or composite materials. In one embodiment, thecore 24 can be formed of woven strap, ribbon, web, fiber, filament orrope material 24 a, wound or wrapped, and bonded together withadhesives, glues or resins 34. The adhesives 34 can be an epoxy typeadhesive and can fill the voids, cavities, recesses or spaces 25 in thecore 24. In some embodiments, the adhesive can be the same adhesive 34used for rim 26. The material 24 a can be secured to shaft 18, such aswith adhesives, glue, or resin 34 and wound under tension to the desireddiameter, and secured in place, such as with adhesives, glue or resin34. The material 24 a can be woven polyester or nylon. In oneembodiment, ½ inch diameter nylon rope can be used. In otherembodiments, the material 24 a can be a flat web having the same widthof the flywheel 12.

In some embodiments, the core 24 can be formed of a suitable metal,which can included stainless steel, various other steels, titanium,etc., that can be machined to be round, concentric and balanced. Such ametallic core can include mechanical features or fasteners forsecurement to the outer composite rim structure 26. A concentric andbalanced metal core 24 can allow the formation of the outer rim 26 to beformed in a manner that can allow the flywheel 12 to be more easilybalanced. The metal core 24 can be easily machined to be concentric, anddoes not become misshapen during the formation of the outer rim 26thereon, which can sometimes occur when core 24 is formed of somecomposite materials.

The outer rim 26 can be formed of a series of, or multiple radial layersof stainless steel material. The stainless steel material can be porous,and mounted or secured to, and wrapped around the core 24, and bondedtogether with adhesives 34. In some embodiments, the adhesive 34 can bea two part epoxy type adhesive having an epoxy resin that is mixed withan epoxy hardener. In one embodiment, the epoxy resin can have a highviscosity of about 10,000 to 15,000 cP, such as about 13560 cP, theepoxy hardener can have a low viscosity of about 10 to 30 cP, such asabout 21 cP, and can be mixed together in about a 78/22 ratio. Whenmixed, the epoxy can have a syrupy viscosity prior to curing, such asabout 590 cP, have a long curing time, such as about 24 to 72 hours, andcan have a shear strength of at least about 1000 PSI when cured, whichcan be 1490 PSI. The epoxy used can be chosen to withstand warmtemperatures, such as typically encountered by a flywheel operating in avacuum enclosure. The stainless steel material in one embodiment can bestainless steel wire rope 30, which for example, can be woundcontinuously under tension to the desired wheel diameter, and can be ½inch in diameter, and can be formed of multiple wire strands, fibers orfilaments. Referring to FIG. 6, the voids, cavities recesses or spaces31 within the wire rope 30 between the wire strands, and the voids,cavities, recesses or spaces 33 between radially and laterally adjacentcourses of wire rope 30 can be filled and occupied by the adhesive 34.This can continuously bond the individual wire strands in the wire rope30 together, as well as continuously bond each radially and laterallyadjacent course of wire rope 30 together. In some embodiments, ifdesired, the wire rope 30 can be a single fiber or filament.

The voids 25 within and around the material 24 a for core 24, and thevoids 31 and 33 within and around the wire rope 30 of the outer rim 26can be filled with adhesive 34, which can be introduced and impregnatedinto the core 24 and outer rim 26 under vacuum. Referring to FIGS. 7-15,a flywheel 12 having a core 24 and outer rim 26 without adhesives can beplaced within the interior 21 of a vacuum chamber, enclosure or housingthat has a dimensionally accurate size and shape of the finishedflywheel. The vacuum enclosure can be similar or the same as enclosure14 of FIG. 1, with appropriate sizing or dimensions, or can be aseparate or different enclosure. The vacuum enclosure 14 can have aclamshell construction with an upper portion or half 14 a and a lowerportion or half 14 b, which can be joined or bolted together at flanges15 a and 15 b for sealing. Each half 14 a and 14 b can be generally onehalf of a disk or cylinder with a half circular outer perimeter of about180°, which when combined, collectively form a vacuum enclosure 14 thatis generally disk or cylindrically shaped. The exterior of each half 14a and 14 b can include ribs or gussets 19 for added strength. Each half14 a and 14 b has an interior region 21 a and 21 b which collectivelyform the interior 21 of vacuum enclosure 14. A sealing flange 23 on eachside of the vacuum enclosure 14 can provide sealing around shaft 18.Each sealing flange 23 can have an upper 23 a and lower 23 b portionassociated with halves 14 a and 14 b which join together.

A vacuum pump 36 can be connected to the vacuum enclosure 14 via aconduit 37 and shut off valve 38, such as at the bottom, and air, water,moisture and gases inside removed, for example, until about 28 to 32inches of mercury vacuum is achieved. The vacuum pump 36 can be shutdown and/or isolated by shut off valve 38. A reservoir 42 of adhesive 34can be connected to the vacuum enclosure 14 via a conduit 40 and shutoff valve 44. The valve 44 can be opened to let the adhesive 34 enterand impregnate the interior of the vacuum enclosure 14, penetrating intoand impregnating the core 24 and/or the outer rim 26 of the flywheel 12,filling in the voids 25 within the core 24, and the voids 31 and 33 inthe outer rim 26. If desired, the reservoir 42 can include a pump forpumping the adhesive 34, or alternatively, a pump can be connected toreservoir 42 or conduit 40. By having a long curing time, for exampleabout 72 hours, the adhesive 34 has sufficient time to seep into andfill virtually all the voids 25, 31 and 33, while under vacuumimpregnation, before curing. Once the adhesive 34 has cooled and set orcured, the impregnated flywheel 12 can be removed from the vacuumenclosure 14. The outer diameter of the flywheel 12 can be machined tobe concentric relative to shaft 18 and the two sides 13 can be machinedflat. In different embodiments, the position of the conduits 37 and 40can be reversed, or located in other positions. Additionally, othersuitable methods of vacuum impregnation can be performed, as known inthe art.

In some embodiments, the flywheel 12 can be about 48 inches in diameteror greater. In one embodiment, the flywheel 12 can be about 120 inchesin diameter, about 48 inches wide, and can have a core 24 that is about90 inches in diameter. It is understood that the width and diameter canbe greater or smaller, depending upon the use and situation at hand.

Referring to FIGS. 16-18, three construction methods of forming theouter rim 26 are depicted. The first method shown in FIG. 16 depictsmetallic or stainless steel wire rope 30 that is attached to core 24,such as by fasteners, adhesives, glue or resin, and wound continuouslyunder tension. The wire rope 30 can be wound side by side in lateralcourses to form each radial course to the desired width, for example 48inches wide. Enough radial courses are wound until the desired diameteris formed, for example, 120 inches in diameter, where it is secured inplace, for example with adhesives, glue or resin. In one embodiment, thecore 24 can be 90 inches in diameter and the outer rim 120 inches indiameter, which can form an outer rim 26 that is 15 inches thick in theradial direction, or about ¼ the total radius of flywheel 12.

The second method shown in FIG. 17 depicts the formation of individual,separate or discrete concentric annular rings 46 of metallic orstainless steel mesh 32 around the core 24. Each ring 46 can consist ofa length of mesh 32 having ends 32 a which can be secured together undertension, for example with a lateral pin 48, one circumference at a time.In other embodiments, other suitable fastening methods can be used, suchas stitching or sewing with wire, locking rings, etc. The mesh 32 can bea relatively flat porous woven wire mesh belt, cloth, screen, ribbon,expanded or perforated metal sheet, having voids 31 in the mesh 32between fibers or members 35 of the mesh 32, and forming voids 33between each concentric annular ring 46. The first ring 46 can besecured to the core 24, such as with fasteners, adhesives, glue orresin, and subsequent rings 46 then being added. In one embodiment, themesh 32 can be the desired width W of flywheel 12, for example, 48inches wide and a sufficient number of rings 46 can be added around a 90inch diameter core 24 to result in an outer diameter of desired size,for example, 120 inches. In some embodiments, the fibers or members 35in the mesh 32 of each ring 46 can interlock with fibers or members 35in the mesh 32 in radially adjacent rings 46. When the adhesive 34 isapplied, the adhesive 34 can fill the voids in the mesh 35 between thefibers or members 35, bonding them together, as well as fill the voids33 for bonding the radial layers of the mesh 32 together.

The third method shown in FIG. 18 depicts a belt of metallic orstainless steel mesh 32 that has been secured to core 24, such as byfasteners, adhesives, glue, or resin, and continuously wound or wrappedin a spiral manner around the core 24 in multiple radial layers undertension until the desired outer diameter is obtained. In someembodiments, the mesh 32 can be the desired width W of flywheel 12,about 48 inches wide, and wound around a 90 inch core 24 until the finaldesired diameter is obtained, for example, about 120 inches. In someembodiments, the wire rope 30 and mesh 32 can be replaced with flatstainless steel wire braid. In other embodiments, the core 24 can beomitted and the outer rim 26 can be formed around or secured to theshaft 18.

The weight of the flywheel 12 can be at least about 1700 lbs and cancommonly have weights of about 5000 lbs, about 10,000 lbs, about 20,000lbs, about 30,000 lbs, about 40,000 lbs, about 50,000 lbs, about 60,000lbs and about 70,000 lbs. At rotational speeds over about 1000 RPM, andranging up to about 10,000 RPM, a large heavy flywheel can commonlyfail. However, the present invention can provide a large heavy flywheel12, having the sizes, weights and rotational speeds previouslydescribed. A large diameter (48 inches or greater) flywheel 12 having aheavy mass or weight (1700 lbs and above), can be formed and can beoperated at high speeds (1000 RPM and above) by forming the outer rim 26from stainless steel bounded together in the manner previouslydescribed. It has been found that stainless steel can have an increasedadhesive bond strength with an adhesive such as epoxy over that ofcommonly available steel metallic wire, which can enable these largesizes, weights and speeds. For example, the use of stainless steelmaterial can form a stronger surface bond with the adhesive 34 incomparison to a metal such as commonly available steel. Commonlyavailable steel forms oxides or rust on its surface which typicallylimits the strength of the surface bond with adhesive 34. If the steelis coated with a substance to limit oxidization or rust, such as oil,the coating also typically limits the strength of the surface bond. Incontrast, by using stainless steel material, oxides, rust or coatingsare typically not present, so that a higher strength surface bondbetween the surface of the stainless steel material and adhesive 34 canbe obtained. If desired, the surface of the stainless steel can betreated to further increase the surface area or form pores orindentations in the surface, for example, by etching, such as with acidsor other suitable chemicals. Mechanical surface treating can also beperformed, such as with an abrasive material or member. Stainless steelhas sufficient strength to be used in a large high speed flywheel 12 andhas desired weight characteristics. In addition, by using stainlesssteel material that is porous and an adhesive 34 that is impregnatedinto the outer rim 26 under vacuum over an extended or a long period oftime, virtually all the voids 31 within the stainless steel material andthe voids 33 between the stainless steel material can be filled withadhesive 34, thereby forming or maximizing a high amount of surface areabonding between the adhesive 34 and the stainless steel material.Furthermore, the filling of the voids 31 and 33 can form interlockingregions of adhesive 34, thereby also providing locking of the layers ofstainless steel material relative to each other. Consequently, theflywheel 12 is able to withstand the high forces during operation due toone or more of the following, the adhesive can form a strong surfacebond with stainless steel material, when the stainless steel materialused is porous with a high surface area, the bonding can be over a highor large surface area which maximizes the amount of bonding, and theadhesive can have a shear strength over about 1000 PSI, such as about1490 PSI.

In addition to the epoxy resin described above, in some embodiments,other types of epoxy resins, can be used, as well as other suitableglues, resins and adhesives, including thermosetting resins. Also,metals or alloys other than stainless steel can be used. For example,common or carbon steel without an oil coating can be employed ifmeasures are taken to compensate for, or prevent rust and corrosion. Thecommon steel can be transported, stored and assembled in a moisture freeenvironment to prevent the formation of rust or corrosion. Furthermore,the surface of the common steel can be surface treated to remove anyrust or corrosion prior to assembly into a wheel. Protective rustinhibiting coatings, such as, metallic or oxide coatings can also beemployed to prevent rust or corrosion from forming. Steel alloys otherthan carbon or common steel, such as 4000 series steel, can be used.Also, other metals used can also include titanium or other suitablemetals, or alloys.

When carbon or common steel, is cleaned and surface treated to removeoil, rust and/or corrosion, the surface can be made more porous andthere can be a stronger initial bond with adhesive 34 than is obtainablewith stainless steel. However, over time, there is a chance that thecarbon or common steel could later rust or corrode if moisture isabsorbed by the adhesive 34, or if the carbon or common steel slowlychemically or galvanically reacts with the adhesive 34, so that the bondof the carbon or common steel with the adhesive 34 can weaken over time.Weakening of flywheel 12 is undesirable in view that a mechanicalfailure of the flywheel 12 can be catastrophic. However, using stainlesssteel can reduce, limit or prevent subsequent rusting or corroding afterbonding with adhesive 34, since stainless steel is resistant to rustingand corroding from moisture, and is also resistant or does notchemically or galvanically react with many or most adhesives 34.Consequently, stainless steel can have a bond strength with the adhesive34 that can remain substantially the same or consistent over time. Inorder to aid or increase the bond strength of the stainless steel withthe adhesive 34, a pre-epoxy primer, such as known in the art, can beapplied to the stainless steel to treat or etch the surfaces prior tobonding with adhesive 34.

Referring to FIGS. 19 and 20, flywheel 50 is another embodiment of aflywheel in the present invention which differs from the flywheel 12made in the manner of FIG. 18, in that the outer rim 26 can be formedaround core 24 with a web of porous stainless steel material or mesh 32and an interlayer web of porous nonmetallic fiber material or cloth 52,lengths of which are continuously wound around the core 24 to form abilayer spiral composite wheel structure or configuration 60, havingalternating layers of mesh 32 and interlayer 52 (FIG. 21) bonded inadhesive 34. The core 24 can be a metallic core that is machined to beround and concentrically mounted to shaft 18, and can be balanced.Securement members 28 can be used to mount core 24 to shaft 18, butalternatively, other suitable securement members or methods known in theart can be employed, such as with keys, splines, etc. The outerperimeter of the core 24 can have a securement or attachment location,structure or fixture 55 for securing the ends of the mesh 32 andinterlayer 52 to the core 24 prior to winding. The securement structure55 can include one or more slots or holes 54 and/or clamping members 56to trap, clamp or secure mesh 32 and interlayer 52 to the outer surfaceof the core 24. The clamping members 56 can be spring loaded, oralternatively, can be tightened with screws or bolts. The webs of mesh32 and interlayer 52 can have a width W that is about the width of theflywheel 50 and can be wound under tension continuously around core 24until the desired diameter is obtained. The final outer layer 58 can bethe interlayer material 52 so that the mesh 32 can be encapsulated andcontained by interlayer 52 and adhesive 34 composite on thecircumferential outer perimeter, which typically has the highest stress.The width W of the flywheel 50 can commonly range from 12 to 48 inches,and the outer diameter can commonly range from 36 to 120 inches indiameter. The flywheel 50 can be bonded together with the same adhesive34 or resin such as epoxy resin, and in the same manner as described forflywheel 12.

The porous nonmetallic interlayer 52 can have a stronger bond with theadhesive 34 than the stainless steel mesh 32 has with the adhesive 34,and the interlayer 52 and adhesive 34 can form a high strength spiralcomposite structure 60 a that is bonded to and continuously spirallyencompasses or sandwiches internally and externally, the spiralcomposite structure 60 b formed by the mesh 32 and adhesive 34, therebyforming a bilayer spiral composite wheel structure 60. The interlayer 52can be a web of woven or nonwoven cloth of suitable materials or fiberssuch as aramid fibers, carbon fibers, glass fibers and carbon nanotubes.The carbon nanotubes can be considered fibers. When the interlayer 52 isformed of carbon, such as carbon fibers or carbon nanotube paper orcloth, the spiral composite structure 60 a can be of higher strengththan spiral composite structure 60 b, and can create an outer compositerim structure 26 that is stronger than the one in flywheel 12. By beingin a bilayer spiral configuration, the mesh 32 in the spiral structure60 b can be continuously adjacently internally and externally supported,bonded to and locked in place by the adjacent sandwiching spiral ofcomposite structure 60 a. The spirally composite structure 60 a canspirally circumferentially surround the spiraling composite structure 60b on the outer radial side while spirally radially outward and canspirally circumferentially and radially lock the composite structure 60b within a high strength structure. As a result, the spiraling compositestructure 60 a can continuously spirally contain or resist in a seriesof integrally connected radial layers, outward centrifugal forces F ofeach radial layer of mesh 32 in the spirally composite structure 60 b,during rotation of flywheel 50.

Referring to FIG. 21, the interlayer 52 can also reduce the size ofspaces or voids 33 between the radial layers in the outer rim 26 incomparison to that in flywheel 12, which can also contribute to higherstrength, since the adhesive 34 can span across smaller voids. Forexample, referring to flywheel 12 in FIG. 18, the fibers or members 35of mesh 32 have cavities, spaces, recesses or voids 31 between thefibers or members 35, and the radial layers of mesh 32 are adjacent toeach other. As a result, the spaces or voids 33 between the radiallayers of mesh 32 can also extend into the cavities or voids 31 withinthe mesh 32, thereby increasing the size of the spaces occupied by theadhesive 34. It is possible for a void 31 in one radial layer of mesh 32to extend into the void 33 between adjacent radial layers of mesh 32 andfurther into a void 31 in the next radial layer of mesh 32, therebycreating a large or long continuous void. The adhesive 34 occupying alarger or longer void can break or shear more easily than an adhesiveoccupying a smaller or shorter void. However, in flywheel 50, as seen inFIG. 21, the interlayer 52 can act as a separator, partition or barrierbetween the adjacent radial layers of mesh 32, separating the radiallayers of mesh 32 apart from each other so that voids 31 in the adjacentradial layers of mesh 32 generally do not extend across space or void 33into the next radial layer of mesh 32. In addition, the interlayer 52can be much thinner than the layer of mesh 32, so that the cavities,voids, recesses or spaces 52 b between the fibers or members 52 a of theinterlayer 52 can be small or short, and if combined with a void 31 inthe radial layer of mesh 32, does not create a much larger or longercombined void than found in the initial void 31. As a result, theadhesive 34 can occupy smaller or shorter voids 31, 33 and 52 b, andhave higher resistance against shear forces. In some embodiments, thefibers or members 32 a and 52 a of adjacent radial layers of mesh 32 andinterlayer 52, can experience some interlocking for providing mechanicallocking and further strength.

In some embodiments, the stainless steel mesh 32 can be about % inchesthick, and can range from about V8 to about ½ inches thick, and theinterlayer 52 can be about 1/32 to 1/16 inches thick, and range fromabout 1/64 to about V8 inches thick. The number of radial layers of themesh 32 and the interlayer 52 depend on the thickness of outer rim 26,as well as the thickness of the mesh 32 and the interlayer 52. Forexample, for embodiments of the outer rim 26 having a thickness that isabout ¼ the total radius, in a flywheel 50 that is 36 inches indiameter, the outer rim 26 can be about 4.5 inches thick in the radialdirection, and can have as little as 8 radial layers, each of mesh 32and interlayer 52 (total of 16), or as many as 32 radial layers each(total of 64). In a flywheel 50 that is 48 inches in diameter, the outerrim 26 can be about 6 inches thick in the radial direction, and can haveas little as 10 radial layers each (total of 20), or as many as 42radial layers each (total of 84). In a flywheel 50 that is 72 inches indiameter, the outer rim 26 can be about 9 inches thick in the radialdirection, and can have as little as 15 radial layers each (total of30), or as many as 64 radial layers each (total of 128). In a flywheel50 that is 120 inches in diameter, the outer rim 26 can be about 15inches thick in the radial direction, and can have as little as 24radial layers each (total of 48), or as many as 107 radial layers each(total of 214). It is understood that the diameter of flywheel 50, theradial thickness of the outer rim and the thickness of the mesh 32 andinterlayer 52 can vary, depending upon the situation, so that the numberof radial layers of mesh 32 and interlayer 52 can vary by a largedegree. The mesh 32 in addition to having configurations or othercounterparts as previously described for flywheel 12, can also includednonwoven porous stainless steel fiber material and chain link or mail.The interlayer 52 can include woven and nonwoven fibers or members 52 aformed into a porous material configuration, cloth or paper (thin clothcan be considered paper), and is most often formed of carbon fibers orcarbon nanotubes for high strength. Although a steel alloy such asstainless steel mesh 32 is preferred, other corrosive resistant steelalloys can be employed, such as molybdenum steel, which can be heavierthan stainless steel. In addition, 4000 series steel can be used, whichis not as corrosion resistant but can be more cost effective, ortitanium can be used. Furthermore, in some embodiments, flywheel 50 canbe made employing the process depicted in FIG. 17, where concentricannular rings of mesh 32 and interlayer 52 are formed and assembledaround core 24. The use of mesh 32 and interlayer 52 formed around aconcentric or round core 24, having a width W that is about the width ofthe flywheel 50, can result in a wheel that is generally easy tobalance.

While this invention has been particularly shown and described withreferences to example embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

For example, it is understood that the dimensions, weight and rotationalspeed of the flywheels described can vary, depending upon the situationat hand.

What is claimed is:
 1. A method of forming a flywheel comprising:forming multiple radial layers of stainless steel material into a wheel;and bonding the multiple radial layers of stainless steel materialtogether with epoxy type adhesive to form a composite rim structure ofthe wheel.
 2. The method of claim 1 further comprising providing theradial layers of stainless steel material with a series of cavities. 3.The method of claim 2, further comprising providing the stainless steelmaterial with a length of stainless steel fibers.
 4. The methods ofclaim 3 further comprising vacuum impregnating the epoxy type adhesiveinto spaces between the stainless steel fibers and the radial layers ofthe stainless steel material.
 5. The method of claim 4 furthercomprising providing stainless steel material comprising stainless steelwire rope.
 6. The method of claim 4 further comprising providingstainless steel material comprising a web of stainless steel braidedwire.
 7. The method of claim 4 further comprising providing stainlesssteel material comprising a web of stainless steel mesh.
 8. The methodof claim 4 further comprising positioning the composite rim structurearound an outer perimeter of a core member.
 9. The method of claim 8further comprising mounting the core member on a central shaft.
 10. Themethod of claim 1 further comprising forming the composite rim structurewith a series of discrete concentric annular rings of stainless steelmaterial.
 11. The method of claim 1 further comprising forming thecomposite rim structure with a continuous spiral wound length ofstainless steel material.
 12. The method of claim 1 further comprisingforming the composite rim structure to include multiple radial layers ofnonmetallic fiber material positioned so that adjacent radial layers ofstainless steel material have a layer of the nonmetallic fiber materialbonded therebetween.
 13. The method of claim 12 further comprisingforming the radial layers of nonmetallic fiber material from carbon. 14.A method of forming a flywheel comprising: forming multiple radiallayers of porous steel web material and multiple radial layers of porousnonmetallic fiber web material into a wheel, with alternating radiallayers of porous steel web material and porous nonmetallic fiber webmaterial; and bonding the multiple radial layers of porous steel webmaterial and multiple radial layers of porous nonmetallic fiber webmaterial together with an adhesive to form a composite rim structure ofthe wheel.
 15. The method of claim 14 further comprising winding theporous steel web material and the porous nonmetallic fiber web materialfrom continuous lengths into a bilayer spiral configuration.
 16. Themethod of claim 14 further comprising forming the porous steel webmaterial from alloy steel.
 17. The method of claim 16 further comprisingforming the porous steel web material from stainless steel.
 18. Themethod of claim 14 further comprising forming the porous nonmetallicfiber web material from carbon.
 19. The method of claim 14 furthercomprising providing the porous steel web material in mesh form and theporous nonmetallic fiber web material in cloth form.
 20. The method ofclaim 14 further comprising positioning the composite rim structurearound an outer perimeter of a metallic core member.
 21. A method offorming a flywheel comprising: forming multiple radial layers of surfacetreated steel material into a wheel; and bonding the multiple radiallayers of surface treated steal material together with an adhesive toform composite rim structure of the flywheel.
 22. The method of claim 21further comprising treating surfaces of the steel to remove at least oneof rust and oil.
 23. The method of claim 21 further comprising treatingsurfaces of the steel to increase surface area for bonding withadhesive.
 24. The method of claim 21 further comprising treatingsurfaces of the steel with a rust inhibiting protective coating.